YouTube Watch Later Telegram Bot

Friends often send me YouTube videos in Telegram DMs or chats.
Some of those videos are even worth watching.
They usually go to "Saved Messages" in Telegram, where are effectively lost after some time.
At the same time, YouTube has a special place for them: a "Watch Later" playlist.
I even watch it periodically, e.g. while cooking.
Opening a video on the phone just to press that "Watch Later" button takes a stupidly lot of time.
So I thought about a Telegram bot who will save the incoming videos to my "Watch Later" playlist.

Enjoy!
And don’t be afraid that I would add some spam into your playlists.
The code is open-sourced (although I am ashamed to share it), the best Harvard alumni crafted my Privacy Policy, and the app successfully passed Google API OAuth Dev Verification.
However, if you are really paranoid but still want to use it — run your own instance, the guide is in README, and free Heroku account will be enough.

A few words about the verification process, for those who are interested in it.
Google has three API access levels for user data: general, sensitive, restricted.
A developer can use the first one without any hassle.
The second requires verification.
Third requires a security assessment, that costs $15К — $75К (or even more).
Sensitive API access level is enough to manage user’s "Watch Later" playlist.
To pass the review you need a publicly accessible web page describing your project, a privacy policy, and a demo video, describing how you use the API to work with user data.
The result of the review was e-mailed to me in a day.
In general, it’s not necessary to pass the review if you don’t plan to surpass one hundred (or so) users limit.